Nutritionally essential polyunsaturated fatty acids[unreadable] (PUFAs) have been implicated as potentially important factors in mood[unreadable] disorders. However, the role of PUFAs in acute mania has been minimally[unreadable] investigated. We performed a pilot study to explore associations between[unreadable] symptom severity and levels of fatty acids and of the cyclooxygenase (COX)-derived arachidonic acid[unreadable] metabolite, prostaglandin E2 (PGE2). Patients (n=10) that were medication-free for at least[unreadable] 2 weeks and seeking inpatient admission for an acute manic episode were[unreadable] compared with healthy volunteers (n=10). Fasting[unreadable] baseline free and esterified plasma levels of docosahexaneoic acid (DHA,[unreadable] 22:6n-3), eicosapentaenoic acid (EPA, 20:5n-3), arachidonic acid[unreadable] (AA,20:4n-6) and the AA metabolite PGE2 were determined, and PGE2[unreadable] levels were tested again at 6 weeks. No significant changes in levels of[unreadable] individual or total fatty acids, or of PGE2 were found. Among subjects, manic[unreadable] symptom severity correlated negatively with levels of free AA and free[unreadable] EPA, and positively with the free AA:EPA ratio. PGE2 levels did not[unreadable] differ between groups or in subjects pre- and post-treatment.[unreadable] These preliminary results suggest that, in susceptible[unreadable] persons, low plasma levels of free EPA compared with AA are related to[unreadable] the severity of mania.